I'm just with some troubles to the chracter make the isometric move, because the isometric movement need to happens on a 30º angle (considering that the horizontal line is a 0º angle), but in the rpgmaker, the diagonal movement is a 45º angle move.
Maybe some script edit can make it, but I don't find in wich line to do such change and neither how to change it xD.
I don't know much about pixel movement scripts but what I've seen of making a diagonal script, to move diagonal is just moving one tile right and one tile down at the same time. So maybe to get a different angle of movement with pixel movement it would be (as an example, I don't know where you'd change this or what to change to) move 2px down and 4px left at the same time for a different diagonal movement angle.
Maybe that will help you, maybe its obvious stuff you already knew haha... but love your work, looking forward to this.